A patent application number is a unique number that is assigned to a patent application after the application is filed. For applications filed with the U.S. Patent and Trademark Office, the application number contains a two-digit series code followed by a serial number consisting of six digits.
The two-digit series code corresponds to the particular type of application or proceeding. For example, utility, plant, and reissue applications contain a series code of 1 – 14 depending on the particular year, while provisional applications include a series code of 60, 61, or 62. The six-digit serial number that follows the series code is assigned chronologically.
A patent application number is assigned immediately after the mail is “opened” by the Office Of Patent Application Processing (OPAP) if the application was mailed. If the application was submitted by EFS-Web the Acknowledgement Receipt will contain the application number.